This invention relates to a cog belt pulley with at least one flange, the pulley having a toothed circumferential surface for engagement of one or more cog belts. The invention relates in addition to a cog belt pulley system having a plurality of such cog belt pulleys.
Cog belt pulley systems are used in machines for coupling a plurality of spaced apart axles by means of cog belts so that one motor suffices for driving all coupled axles. The drive of more than two axles can be guaranteed by one cog belt by guiding said belt over a corresponding number of cog belt pulleys. However, a separate cog belt can also be provided per axle pair (cascade arrangement).
The flange for in particular preventing the belt from laterally slipping off the cog belt pulley during operation is usually formed by a flanged wheel disposed on one or both faces of the cog belt pulley. U.S. Pat. No. 3,918,515 and FR 2 520 466 A also disclose forming the flanged wheels of individual segments, the segments being distributed over the total circumference of the cog belt pulley.
However, the presence of the flanged wheels poses a problem during mounting and replacement of cog belts. Since the mounted belt requires an at least small pretension to guarantee reliable engagement with the pulley in operation even at high loads and high speeds. It is not readily possible to lay the belt easily on preassembled cog belt pulleys over the flanged wheels. This problem can be avoided by mounting the flanged wheel only after laying the belt on the pulley, or by swiveling the pulley into the operating position and locking it only after laying on the belt, or by using a belt with overlength and pretensioning it by means of a separate tension roller only after mounting it. These solutions involve considerable constructional effort, however.
In particular in relatively complex machines, such as bank note processors, in which numerous axles are coupled in cascade arrangement via a plurality of cog belts, the constructional effort of the machine and the maintenance effort for changing belts become extremely great.